1. Field of the Invention
This invention relates to an apparatus for measuring a transpiration amount, more specifically, to an apparatus suitable for measuring an amount of water transpired locally from the skin surface, ocular surface or the like.
2. Description of the Related Art
The amount of water transpired locally from the skin surface or the like has conventionally been determined using an apparatus, as illustrated in FIG. 19, comprising a cylindrical body 100 having an opened top and bottom; and two humidity sensors, that is, an upper humidity sensor 200 and a lower humidity sensor 300 disposed inside of the body. Described specifically, a water transpiration amount per unit time and unit area is determined from the difference between the values measured by these two humidity sensors 200 and 300 by making use of the fact that the water concentration at a position upwardly farther from the skin surface is smaller.
The conventional apparatus is however accompanied with the problem that owing to a tendency to be influenced by the external circumstances such as wind, it cannot be always used for measurement at a desired place and what is more important, stable data cannot be obtained easily. In addition, the conventional apparatus involves the drawback that it takes time as long as 1 minute or greater to complete measurement even if an automatic measuring instrument is connected to it, because the absence of a noise must be confirmed upon measurement. A large-scale apparatus is therefore necessary for measurement with excellent accuracy in a short time, but in practice, such an apparatus is utterly unsuited for local measurement of the skin surface or the like.